Fabrication of orifices

ABSTRACT

A method and apparatus for fabricating an aperture of predetermined cross-sectional area in an orifice plate for use in a non-contact printer, includes the steps of fabricating in the orifice plate an aperture of cross-sectional area no less than the predetermined cross-sectional area, flowing an electrolytic deposition solution under pressure through the aperture, applying a constant frequency stimulating disturbance to the stream of electrolytic deposition solution emerging from the aperture, placing an electrically conductive surface in the path of the stream and at a distance from the orifice plate equal to the unbroken filament length of said stream through an aperture of the predetermined cross-sectional area, causing the deposition solution to deposit on the walls of the aperture by connecting the orifice plate and the electrically conductive surface to opposite sides of a source of electric potential whereby the unbroken filament comprises part of the closed electro-deposition circuit, and continuing to supply the electrolytic deposition solution to the aperture until the aperture attains the predetermined cross-sectional area thereby producing filament breakup ahead of the electrically conductive surface and automatically opening the electro-deposition circuit.

United States Patent Taylor 154] FABRICATION OF ORIFICES [72] Inventor:Richard P. Taylor, Chillicothe, Ohio 73] Assignee: The Mead Corporation,Dayton, Ohio [22] Filed: June 15, 1970 [2]] Appl. No.: 46,395

Primary Examiner-John l-l. Mack Assistant Examiner-T. TufarielloAttorney-Marechal, Biebel, French & Eng

[1 3,655,530 [45] Apr. 11,1972

[57] ABSTRACT A method and apparatus for fabricating an aperture ofpredetermined cross-sectional area in an orifice plate for use in anon-contact printer, includes the steps of fabricating in the orificeplate an aperture of cross-sectional area no less than the predeterminedcross-sectional area, flowing an electrolytic deposition solution underpressure through the aperture, applying a constant frequency stimulatingdisturbance to the stream of electrolytic deposition solution emergingfrom the aperture, placing an electrically conductive surface in thepath of the stream and at a distance from the orifice plate equal to theunbroken filament length of said stream through an aperture of thepredetermined cross-sectional area, causing the deposition solution todeposit on the walls of the aperture by connecting the orifice plate andthe electrically conductive surface to opposite sides of a source ofelectric potential whereby the unbroken filament comprises part of theclosed electro-deposition circuit, and continuing to supply theelectrolytic deposition solution to the aperture until the apertureattains the predetermined cross-sectional area thereby producingfilament breakup ahead of the electrically conductive surface andautomatically opening the electro-deposition circuit.

6 Claims, 4 Drawing Figures PATENTEDAPR 1 1 I972 unnu Ill lNl/E/VT'ORRICHARD a TAYLOR A TTOR/VEYS .OEDROP GENERATORS, Ser. I968 and-now U.S.Pat. No. 3,560,641 and assigned to the as- I that the filament length ofthe stream length. Such variations in length of the filament gives riseto :loss of resolution in printing.

"parent from the following description,

FABRICATION OF ORIFICES This application is related to copendingapplication IMAGE CONSTRUCTION SYSTEM USING MULTIPLE ARRAYS No. 768,790,filed Oct. 18,

signee of the present invention.

. BACKGROUND OF THE INVENTION In making apertures in orifice plates foruse in high speed non-contacting printers, as hereinafter described, ithas been found that such apertures or holes must be uniform in size soof liquid does not vary in Asmore fully described in said copendingapplication Ser.

"No. 768,790, liquid under pressure is forced through apertures in anorifice plate. The drop generating system is stimulated at a selectedfrequency to induce formation of equally sized drops at the end of theliquid filaments issuing from the "apertures. The drops are thenselectively charged by charging rings, and pass through a deflectionfield, to be directed either into a catcher for removal from the system,or to deposit in predetermined locations on a moving web.

To facilitate high speed printing,an array of orifice plates is employedwith a. corresponding increase in the number of apertures. The presenceof a great number of apertures requires that they be of sufficientuniformity in size to minimize loss inthe resolution and clarity of theprinted material.

SUMMARY OF THE INVENTION The present invention employs a method andapparatus to produce uniform apertures for use in a non-contact printingsystem.An orifice plate is provided with pre-formed apertures or holes,the diameter of the holes being at least the size of the predetermineddiameter desired. Liquid is supplied to the orifice plate underpressure. The liquid supplied is an electrolytic solution containing,for example, nickel ions, and is flowed through each aperture or holein. the orifice plate. Suitable bar. A potential difference is brokenfilament reaches the contact bar. As a result, metal from theelectrolyte liquid is caused to deposit or plate on the wall ofthe'apertures.

An unbroken filament of liquid issues from the apertures,

"but has the tendency of subsequently breaking into drops. The length ofthis filament is dependent primarily upon fluid pressure, fluidviscosity, stimulation frequency and the diameter or cross-section ofthe apertures. As the deposition builds up on the inside of theapertureand decreases the diameter of the aperture, the filament lengthwill shorten, eventually not reaching and impinging on the contact bar.As a result, the

electric circuit is opened, and deposition inside the apertures .ceases.Therefore, by varying the distance of the contact bar from. the orificeplate, the diameter of the apertures can be controlled.

The primary object of this invention is, therefore, to provide such.amethod of forming small apertures to predetermined size, and to provideapparatus for this method.

- Other objectsand advantages of the invention will be aptheaccompanying .drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of theuniform aperture forming device;

'FIG. 2 is a diagrammatic fragmentary view of the device;

FIG. 3 depicts an assembled drop generator unit; and

FIG. 4 is an enlarged view of a single aperture.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a fluidreservoir 10 has a fluid supply line 11 and a stimulator 12 attachedthereto. The orifice plate 15 has apertures or holes 17 predrilled orotherwise formed to a diameter not less than the predetermined desireddiameter. A contact bar 20 is positioned below orifice plate 15. Inorder that the apertures 17 will attain uniform cross-sectional areas,bar 20 is positioned directly below orifice plate 15 and paralleltherewith. Bar 20 and orifice plate 15 are each connected to oppositesides of a DC. potential difference source 22. In the usual case theions in the electrolytic solution will carry a positive electricalcharge, so potential source 22 will ordinarily be connected on thepositive side to contact bar 20 and on the negative side to orificeplate 15. This relation will cause the contact plate to act as the anodein the circuit.

To obtain apertures of uniform cross-sectional area, the plate 15 isfitted to the reservoir, and an electrolytic solution is caused to flowinto reservoir 10 through fluid supply line 11, as indicated in FIG. 2.Stimulator 12 induces drops 25 to form at the end of liquid filaments 30at a frequency equal to the oscillation frequency of stimulator 12. Whena filament impinges on bar 20, the electric circuit is complete, andmetal from the electrolytic solution is caused to deposit or plate onthe inside walls of apertures 17, as seen in FIG. 4. As thecrosssectional area of each aperture 17 decreases in size, the length ofthe corresponding filament 30 decreases until the point of dropformation is above the bar 20. Since only drops are now reaching bar 20,the circuit is broken as to the corresponding filament, and electrolyticdeposition in the aperture ceases. Thus, by controlling the stimulationfrequency and the distance X between orifice plate 15 and bar 20,uniformly sized apertures 17 may be obtained. Each one is controlled insize independently of the others.

In contrast to usual electroplating procedures the coating ions of thisinvention are supplied from a continually flowing fluid rather than fromthe anode of electrodeposition circuit. This means that the anode may beany conductive material such as graphite. However, the contact plateshould not be made of a material which will be coated by the ions fromthe fluid since deposition of the ions on the contact plate willdecrease the anode-orifice distance. Even the plating liquid itself mayserve as an anode if it is pooled below the orifice plate and held at aconstant level. Conversely it is desirable that the anode not functionas a donor of coating material because the accompanying etching of theanode surface would increase the anode-orifice distance.

FIG. 3 depicts a drop generator employing an aperture 17 fabricated bythe above method and apparatus. Liquid, such as ink, is pumped intochamber 31 in a top bar 32 and passes to the aperture 17 formed inorifice plate 15, now fastened beneath this chamber. The resultingliquid filaments 34 break into drops, and a stimulating means in theform of vibrator 35 causes the drops to form at a frequency which iscommon to all filaments, resulting in drops of essentially equal sizeand spacing.

Beneath the orifice plate is gasket 36, and a charging assembly in theform of plate 37 having openings in which charging electrode rings 38are carried. Suitable electrical insulation (not shown) is providedbetween rings 38, such as by an insulating coating on plate 37.

A spacer plate 42, of electrically insulating material, is fastenedbelow the charging assembly. Below the spacer plate is grounded guardelectrode plate 44 on top of an electrostatic deflection assembly,comprising insulating support bars 45 mounting deflection electrodes 47across which a substantial potential difference is applied. Unchargeddrops follow a straight trajectory and deposit on moving web 50, whichpreferably is moved at constant velocity correlated to the dropgenerating frequency so that a continuous line of drops will cause anessentially continuous mark or trace along the web. Charged drops willfollow a curved trajectory due to the deflecting field, and these dropsare removed from the system through a catcher assembly 55.

Although the present invention has been described with reference tofabricating uniform apertures for use in a noncontacting printingsystem, it is to be understood that the present invention may beemployed for any other purpose where apertures of uniform size aredesired, e.g., in fabricating nozzles for a fuel injection apparatus.

While the method herein described, and the form of apparatus forcarrying this method into effect, constitute preferred embodiments ofthe invention, it is to be understood that the invention is not limitedto this precise method and form of apparatus, and that changes may bemade in either without departing from the scope of the invention.

What is claimed is:

1. The method of fabricating an aperture of predeterminedcross-sectional area in an orifice plate comprising the steps of:

a. forming in the orifice plate an aperture of cross-sectional areagreater than said predetermined cross-sectional area,

b. flowing an electrolytic deposition solution under pressure throughthe aperture,

c. applying a constant frequency stimulating disturbance to the streamof electrolytic deposition solution emerging from the aperture,

d. placing an electrically conductive surface in the path of said streamand at a distance from the orifice plate corresponding to the maximumunbroken filament length for an aperture having said predeterminedcross-sectional area,

e. causing the deposition solution to deposit on the aperture byconnecting the orifice plate and said electrically conductive surface toopposite sides of a source of DC. electric potential whereby theunbroken filament comprises part of the electrodeposition circuit, and

f. continuing to supply electrolytic deposition solution through theaperture until the aperture attains said predetermined cross-sectionalarea and thereby causes filament breakupahead of the electricallyconductive surface and interrupts the electrodeposition circuit.

2. The method defined in claim 1 wherein said orifice plate contains aplurality of apertures and said conductive surface is equally spacedfrom said apertures.

3. Apparatus for fabrication of an aperture of predeterminedcross-sectional area in an orifice plate comprising a. an orifice platehaving at least one aperture of cross-sectional area greater than saidpredetermined cross-sectional area,

b. means for flowing an electrolytic deposition solution under pressurethrough the aperture,

c. means producing stimulation of a predetermined constant frequency tothe filament of deposition solution issuing from the aperture,

d. an electrically conductive surface mounted in spaced relation to saidorifice plate such that said surface intercepts the path of said streamand at a distance from said orifice plate equal to the maximum unbrokenfilament length of said stream for an aperture having said predeterminedcross-sectional area, and

e. means connecting said orifice plate and said electrically conductivesurface to opposite sides of a source of DC. electric potential wherebythe unbroken filament comprises part of an electrodeposition circuitcausing the deposition solution to deposit on the aperture walls untilthe aperture attains its predetermined cross-sectional area therebyproducing filament breakup ahead of the electrically conductive surfaceand automatically opening the electrodeposition circuit.

4. The apparatus defined in claim 3 wherein the orifice plate contains aplurality of apertures and said conductive surface is mounted parallelto said orifice plate to insure opening of the electrodepositioncircuits at the same time as filament length breakup and thereby toproduce all of the apertures of the same size.

5. The apparatus defined in claim 3 wherein the source of DC. electricpotential is connected on its positive side to said electricallyconductive surface and on its negative side to said orifice plate.

6. The method of producing a plurality of equal liquid filaments of thesame size and forming equally sized drops from each filament, comprisingthe steps of:

a. forming in an orifice plate a plurality of apertures ofcross-sectional area greater than said predetermined cross-sectionalarea,

b. flowing an electrolytic deposition solution under pressure throughthe apertures,

c. applying a constant frequency stimulating disturbance to all of thestreams of electrolytic deposition solution emerging from the apertures,

d. placing an electrically conductive surface in the path of saidsolution streams and at a distance from the orifice plate correspondingto the maximum unbroken filament length for an aperture having saidpredetermined crosssectional area,

e. causing the deposition solution to deposit in the apertures byconnecting the orifice plate and said electrically conductive surface toopposite sides of a source of DC. electric potential whereby theunbroken solution filaments comprise part of the electrodepositioncircuit,

f. continuing to supply electrolytic deposition solution through theapertures until each aperture attains said predetermined cross-sectionalarea and thereby causes the associated solution filament to break upahead of the electrically conductive surface and interrupt theelectrodeposition circuit,

g. incorporating the orifice plate in a drop generator including achamber for supply of liquid from a common source to all of theapertures,

h. supplying liquid under a predetermined constant pressure to thechamber to create a filament of liquid from each orifice, and

i. stimulating all of the liquid filaments at a common constantfrequency to create equal drops off each filament.

2. The method defined in claim 1 wherein said orificE plate contains aplurality of apertures and said conductive surface is equally spacedfrom said apertures.
 3. Apparatus for fabrication of an aperture ofpredetermined cross-sectional area in an orifice plate comprising a. anorifice plate having at least one aperture of cross-sectional areagreater than said predetermined cross-sectional area, b. means forflowing an electrolytic deposition solution under pressure through theaperture, c. means producing stimulation of a predetermined constantfrequency to the filament of deposition solution issuing from theaperture, d. an electrically conductive surface mounted in spacedrelation to said orifice plate such that said surface intercepts thepath of said stream and at a distance from said orifice plate equal tothe maximum unbroken filament length of said stream for an aperturehaving said predetermined cross-sectional area, and e. means connectingsaid orifice plate and said electrically conductive surface to oppositesides of a source of D.C. electric potential whereby the unbrokenfilament comprises part of an electrodeposition circuit causing thedeposition solution to deposit on the aperture walls until the apertureattains its predetermined cross-sectional area thereby producingfilament breakup ahead of the electrically conductive surface andautomatically opening the electrodeposition circuit.
 4. The apparatusdefined in claim 3 wherein the orifice plate contains a plurality ofapertures and said conductive surface is mounted parallel to saidorifice plate to insure opening of the electrodeposition circuits at thesame time as filament length breakup and thereby to produce all of theapertures of the same size.
 5. The apparatus defined in claim 3 whereinthe source of D.C. electric potential is connected on its positive sideto said electrically conductive surface and on its negative side to saidorifice plate.
 6. The method of producing a plurality of equal liquidfilaments of the same size and forming equally sized drops from eachfilament, comprising the steps of: a. forming in an orifice plate aplurality of apertures of cross-sectional area greater than saidpredetermined cross-sectional area, b. flowing an electrolyticdeposition solution under pressure through the apertures, c. applying aconstant frequency stimulating disturbance to all of the streams ofelectrolytic deposition solution emerging from the apertures, d. placingan electrically conductive surface in the path of said solution streamsand at a distance from the orifice plate corresponding to the maximumunbroken filament length for an aperture having said predeterminedcross-sectional area, e. causing the deposition solution to deposit inthe apertures by connecting the orifice plate and said electricallyconductive surface to opposite sides of a source of D.C. electricpotential whereby the unbroken solution filaments comprise part of theelectrodeposition circuit, f. continuing to supply electrolyticdeposition solution through the apertures until each aperture attainssaid predetermined cross-sectional area and thereby causes theassociated solution filament to break up ahead of the electricallyconductive surface and interrupt the electrodeposition circuit, g.incorporating the orifice plate in a drop generator including a chamberfor supply of liquid from a common source to all of the apertures, h.supplying liquid under a predetermined constant pressure to the chamberto create a filament of liquid from each orifice, and i. stimulating allof the liquid filaments at a common constant frequency to create equaldrops off each filament.